Mordanting process for color printing materials

ABSTRACT

A mordanting process for color printing materials which comprises using a dispersion of fine coacervate particles prepared by reacting a polymer having a cationic nitrogencontaining group which acts as a mordant for a dye having an anionic group and diffusible in an aqueous medium and a phthalic acid derivative of gelatin, polyvinyl alcohol or starch in an aqueous binder. Examples of said polymer having the nitrogencontaining group are poly-2-vinyl pyridine, methyl ptoluenesulfonate of poly-4-vinyl pyridine, poly-4-vinylbenzyltrimethyl ammonium chloride, poly-4-vinylbenzyl-triethanol ammonium chloride, benzyl chloride of polymethacrylic acid dimethylamino ethanol ester, acetate of partially amino guanidized polyvinyl methyl ketone, and aminoguanidized dialdehyde starch.

United States Patent [1 1 Ohyama et al.

[54] MORDANTING PROCESS FOR COLOR PRINTING MATERIALS [75] Inventors: Yasushi Ohyama, Takatsuki;

Sadayuki Miyazawa, Kyoto, both of Japan [73] Assignee: Mitsubishi Paper Mills, Ltd., Tokyo,

Japan [22] Filed: Mar. 9, 1971 [21] Appl. No.: 122,520

[30] Foreign Application Priority Data Mar. 10, 1970 Japan 45/19759 [52] US. Cl 96/57, 96/29 D, 96/53,

[51] Int. Cl G03c 7/00 [58] Field of Search 96/57, 84 A [56] References Cited UNITED STATES PATENTS 2,548,564 4/1951 Sprague et al. 96/84 A 3,271,147 9/1966 Bush 96/57 deh fie sta h;

[ Nov. 20, 1973 Ohyama et al 96/57 Cohen et al. 96/57 1 ABSTRACT A mordanting process for color printing materials which comprises using a dispersion of fine coacervate particles prepared by reacting a polymer having a cationic nitrogen-containing group which acts as a mordant for a dye having an anionic group and diffusible in an aqueous medium and a phthalic acid derivative of gelatin, polyvinyl alcohol or starch in an aqueous binder. Examples of said polymer having the nitrogencontaining group are poly-Z-vinyl pyridine, methyl p-toluenesulfonate of poly-4-vinyl pyridine, poly-4- vinylbenzyl-trimethyl ammonium chloride, poly-4- vinylbenzyl-triethanol ammonium chloride, benzyl chloride of polymethacrylic acid dimethylamino ethanol ester, acetate of partially amino guanidized polyvinyl methyl ketone, and aminoguanidized dial- 7 Claims, No Drawings MORDANTING PROCESS FOR COLOR PRINTING MATERIALS The present invention relates generally to an improved mordanting process for color printing materials and more particularly it relates to an improved mordanting process for forming on a support such as a paper or a film a fast and sharp dye image having clear colors and excellent resolving power.

The process of this invention is generally applicable to any photographic processings for providing dye images. That is, the process of this invention can be used in case of transferring a dye or dyes from a matrix having absorbed therein an acid dye or acid dyes to a dyetransfer paper or a dye receiving paper by a well-known color printing process such as an imbibition process or a dye transfer process or can be also used in case of fixing diffusible dye developer molecules in the transfer layer of a final image-receiving support when a color print is formed by a Polacolor system of International Polaroid Corp. disclosed in, e.g., Japanese Pat. Publication No. 182/59 or 444/63. Furthermore, the process of this invention can be utilized in such color photographic process as disclosed in, e.g., British Pat. No. 840,731 or Japanese Pat. Publication No. 15,745/69 in which diffusible dyes formed by a color development are transferred by diffusion in a transfer layer or also in case of introducing an acid bleaching azo dye in a light sensitive emulsion layer by a photographic process well-known as a silver dye bleaching method. Moreover, the invention can be utilized in intermediate layers, a filter layer, and an antihalation layer for a multiple layer type color photographic lightsensitive element.

The principle of the present invention is common to these any cases as mentioned above. That is, the principle of the present invention is a technique of fixing in a desired photographic emulsion layer a dye or a coloring matter having a so-called acid group capable of endowing the molecule with water solubility or with a diffusing property in an aqueous medium, such as a hydroxyl group, a carboxyl group, or a sulfone group, the technique corresponding to mordanting usually used in the field of dyeing. ln the principle of this invention such property of the aforesaid anionic dye or coloring matter as forming a complex when comes into contact with a cationic nitrogen-containing base.

The cationic nitrogen-containing bases have usually been used as mordants for acid dyes in dyeing but such bases are used for the purpose only when they have considerably large molecular weight and a sufficient adsorption power to fibers. If the molecular weights of them are small, the complexes formed from them become, on the contrary, diffusible in an aqueous medium and hence they are used, in such case, as only a decoloring accelerator in discharging.

Different from dyeing of fibers, even if a dye or nitrogen-containing base having a somewhat larger molecular weight is employed in coloring or photographic layers containing as a binder gelatin, polyvinyl alcohol, hydroxyethyl cellulose or other water-soluble polymer, the adsorption power of the dye or the base to gelatin or the other water-soluble binders is insufficient and the dye will flow away, ooze and transfer into other photographic layers during processing. Therefore, it is usually necessary to increase further the molecular weight of the nitrogen-containing base itself.

However, different polymers are general immiscible uniformly each other. For example, gelatin may be, at a glance, completely mixed with polyvinyl alcohol when they are maintained at a high temperature but the mixture will frequently cause phase separation when the mixture is cooled. Also, a copolymer of, for example, vinyl methyl ether and maleic anhydride causes aggregation and forms an extraordinarily high viscous material when the copolymer is mixed with gelatin or polyvinyl alcohol, which results in forming percipitates insoluble in water even in an acid state. Thus, the cationic nitrogen-containing material as mentioned above is more apt to be aggregated and is difficult to be uniformly mixed when it is mixed with amphoteric polymer such as gelatin owing to the cationic property as well as mixed with polyvinyl alcohol owing to the coaction between the OH group and the nitrogen base.

Now, the nitrogen-containing base polymers used in this invention may be known polymers or similar ones and are not limited to specific ones. The typical examples of the polymers used in this invention are poly-2- vinyl pyridine shown by the following formula (I), methyl p-toluenesulfonate of poly-4-vinyl pyridine having the formula (II), poly-4-vinylbenzyl-trimethyl ammonium.chloride having the formula (III), poly-4-vinylbenzyl-triethanol ammonium.chloride having the formula (IV), benzyl chloride of polymethacrylic acid dimethylamino.ethanol ester having the formula (V), the acetate of partially amino-guanidized polyvinyl methyl ketone having the formula (Vl), and aminoguanidized aldehyde starch having the following formula (VII);

CHzOH CHzOH CH-CH CHzOH said symbols n and m representingjnieegers In case of a polymer of quaternary ammonium salt, various variations may be formed by substituting the alkyl group or benzyl group to be introduced into the nitrogen atom of the polymer for other alkyl group or a similar group such as an aralkyl group or a hydroxyalkyl group or by varying the extent of the quaternarization and also the property of the polymer may be varied by varying the polymerization degree thereof of by copolymerizing it with other vinylic polymer. Many of these polymers including the copolymers are known, have widely used as mordants for dyeing and other uses, and may be prepared by well-known methods. These materials are well adsorbed on fibers or fabrics and hence are suitable for the purpose of mordanting in ordinary dyeing but when they are mixed with a water-soluble polymer such as gelatin, polyvinyl alcohol, hydroxyethyl cellulose, etc., for coloring photographic layers, troubles are apt to occur as mentioned before. The occurrence of such troubles may be less if the addition amount of them is as small as less than 5 percent but for adsorbing effectively the diffusible dye onto a water-soluble binder such as gelatin as in the case of this invention, it is considered to be necessary to add such polymer in an amount of 20-30 percent based on the dry weight of the water-soluble polymer as the binder, although the amount may depends upon the content of the active groups in the polymer. When such a large amount of the polymer is mixed with the water-soluble polymer such as gelatin, the occurence of precipitation or phase separation in the mixed system is further increased, the aforesaid troubles are furthermore apt to occur by the presence of the anionic diffusible dye, and hence blurs and aggregations which are not observed as they are become apparently perceptible as the result of coloring.

The principal object of this invention is to remove these difficulties by utilizing, contrary, the co-action of the cationic polymer and other anionic polymer, that is, by utilizing a phenomenon very similar to the aforesaid precipitation or aggregation action.

That is, in this invention, a phthalic acid derivative of gelatin, polyvinyl alcohol or a starch is caused to react with the cationic nitrogen-containing mordant mentioned above in an aqueous solution containing other watersoluble binder as a protective colloid to form fine coacervate particles having particle size of about 0.1- microns and the stable dispersion thus prepared is utilized.

A well-known phenomenon as coacervation is obtainecl by mixing gelatin particularly such gelatin as being prepared by an acid method with gum arabic in a diluted solution thereof and then acidifying the solution with hydrochloric acid or acetic acid and the mechanism for the coacervation is believed to occur by that gum arabic which is an anionic polymer containing a large proportion of carboxylic residual groups is reacted with gelatin which is amphoteric polymer showing cationic property at an acid state in the acidified solution to form a complex and since the water-soluble groups are protected by the complex and the proportion of the water-soluble groups is greatly reduced, undissolved particles are precipitated as oil drops and in this case in order that fine oil drop-like particles are formed without forming large precipitates or aggregates, it is important the balance of the hydrophilic property and the hydrophobic property (or exactly oleophilic property) of the both polymers is in a proper range.

In the process of this invention one of the reactants is a nitrogen-containing cationic high molecular material and the other is a phthalic acid derivative of gelatin, polyvinyl alcohol, or a starch prepared by acetylating a part or the whole part of the NI-l group or the OH group of the polymer with phthalic acid to form an amide or an ester. In the case of gelatin the phthalic acid group is introduced into the e-amino group or the lysine or oxylysine group thereof, while in the case of polyvinyl alcohol or a starch the phthalic acid group is introduced into the alcoholic OH group thereof as shown in the below-showing formulas. In the phthalic acid derivative, the polymer has one free carboxyl group per one substituent and the polymer shows anionic property by a large proportion of the carboxyl groups, thus when the anionic polymer is brought into contact with the cationic polymer as mentioned above in an aqueous solution, they form a complex in a wide range of pH.

On the other hand, when a water-soluble polymer such as gelatin, polyvinyl alcohol or a starch is modified by other dibasic acid than phthalic acid, the points that the polymer becomes anionic by the free carboxyl group per one substituent and also the polymer forms a complex when it is brought into contact with a cationic polymer may be same as the case of the phthalic acid derivative but they not always cause coacervation, that is, even if a phase separation may occur, only two separate layers are formed and oil drop-like coacervates having proper size are not generally formed.

In this point, the phthalic acid derivative of the water-soluble polymer shows specific action, that is, it is considered that by a large number of orthosubstituted benzol nuclei arranges in the molecular chain as shown in the following formulas,.the anionic polymer is endowed with a proper hydrophilic property, the balance of the hydrophilic property and the hydrophobic property of the complex formed is controlled to a proper hydrophobic side, and a phase separation is caused to provide a dispersion of fine oil droplike complex aggregations having a suitable size in an aqueous solution. Thus, a stable dispersion as a dispersion formed by dispersing benzene in water with the aid of an anionic surface active agent is obtained.

Gelatin derivative:

R O R Polyvinyl alcohol derivative:

Starch derivative:

where n is an integer However, because the coacervation becomes considerably unstable as the results of losing the action of the hydrophilic groups of the both polymers by the formation of the complex, when the concentration of the system is high, the coacervation does not occur smoothly as in the case of employing gelatin and gum arabic and further in the case of coloring the coacervates thus formed, the coacervates are apt to be broken and aggregated. On the other hand, it has been discovered that when the coacervation is conducted in a nonchar ging water-soluble polymer such as gelatin, polyvinyl alcohol, polyacrylamide, hydroxyethyl cellulose, hydroxypropyl starch, etc., coacervates are formed very easily even in a high concentration, the size of the coacervates is generally small and the coacervates are very stable, and also the coacervates can be desirably dyed in the state of dispersion.

In addition, the coacervate particles which are fine aggregates by the process as mentioned above are very fine particles that can be observed by only an optical microscope, having usually a grain size of about 0.1-10 microns, the dispersion is an almost transparent milky emulsion or a slightly dense emulsion, and when the dispersion is formed into a thin film and dried, the film becomes completely transparent since the refractive index of the protective colloid becomes same as that of the coacervate particles. Accordingly, when the layer of the fine coacervates is colored or dye-transferred by a diffusible dye, the layer looks by the naked eye as if the layer had been colored uniformly in a non-particle like state.

Now, the production of the phthalic acid derivatives used in this invention will be explained. The phthalic acid derivative of gelatin may be prepared by reacting parts by weight of gelatin and 7 parts by weight of phthalic anhydride as disclosed in, e.g., US. Pat. No. 2,525,753 (1950). In this case, the reactive amino groups have been almost substituted and even by the substitution degree of such extent, the purpose of this invention can be sufficiently obtained since gelatin itself has a hydrophobic (or oleophilic) property. In the case of the phthalic acid derivative of polyvinyl alcohol, a highly substituted derivative having, on an average, one substituent per 2 vinyl alcohol units (substituted percentage of 50 percent prepared by reacting 100 parts by weight of polyvinyl alcohol and more than 300 parts by weight of phthalic anhydride is suitable. Such a phthalic acid monoester of polyvinyl alcohol can be easilyprepared by reacting polyvinyl alcohol and phthalic anhydride in glacial acetic acid using anhydrous sodium acetate as the catalyst by an ordinary manner as in the case of producing a phthalic acid ester of cellulose.

Also, it has been discovered that as the phthalic acid derivative of a starch, the derivative having, on an average, one phthalic acid residual group per one glucose unit (substituted percentage of about 33 percent) prepared by reacting l00 parts by weight of a starch having a comparatively small molecular weight, such as water soluble starch or dextrin and about parts of phthalic anhydride at normal temperature in a solvent such as formamide, dimethyl sulfoxide, and the like is suitable. Furthermore, because different gelatin, starch itself is not completely dissolved in water and remains as a colloidal dispersion even if it is gelled and also starch is weak soluble in cold water, which makes the handling of it troublesome, many derivatives of starch in which a part of the OH groups has been modified to make them soluble in cold water are commercially available, for example, hydroxypropyl starch, hydroxy ethyl starch, carboxymethyl starch and the'like are commercially available and because the degree of the modification of such conventional starch derivatives is generally low, the phthalic acid monoester of starch used in this invention may be prepared by using such commercially available starch derivativeas the raw material. In such case, the balance of the hydrophilic property and the hydrophobic property of such phthalic acid derivative is different from that of the derivative prepared by using starch itself as the raw material and also carboxymethyl starch has already been endowed with anionic property but by adjusting the extent of the introduction of phthalic acid group in accordance with these differences and also by suitably selecting the cationic polymer to be used together with the phthalic acid derivative, the conditions for forming suitable coacervation can be obtained. Thus, such a case is very profitable in the point of increasing the selectability for the combination of the polymers and thus the case is as a matter of course included in the scope of this invention. In addition, the phthalic acid monoester of starch may be prepared by the process described in the specification of Japanese Pat. application No. lOO,750/'69 filed previously by the same inventors and entitled of Process for the production of microcapsules but the process in which starch is dissolved in formamide or dimethyl sulfoxide by heating and after cooling the starch is caused to react with phthalic anhydride at a comparatively low temperature using anhydrous sodium acetate (or potassium acetate) or potassium carbonate is most preferably used.

Furthermore, the fact that the optimum degree of substitution by phthalic acid is greatly influenced by the kind of the hydrophilic polymer to be used as the raw material as mentioned above is caused by that the coacervation greatly depends upon the delicate balance of the hydrophilic property and the hydrophobic property of the both polymers to be reacted each other as mentioned above also. Therefore, the optimum condition also relates to the balance of the hydrophilic property and the hydrophobic property of the cationic base molecule which is one component for the reactants of causing coacervation and is also varied by the conditions (temperature, pH, concentration, etc.), for the coacervation. Thus, the above-mentioned optimum degree of substitution is a rough estimate and shall not be limited to them or shall be selected experimentally about each case.

In the present invention, a mixed derivatives of a dibasic acid and/or monobasic acid can be clearly used. For example, a mixed derivatives of phthalic acid and maleic acid or acetic acid is useful. For example, a mixed derivatives of maleic acid and phthalic acid has such merit that since the derivatives have generally the action of being hardened by causing cross linking by themselves by the presence of the double bond of maleic acid, the derivatives are hardened spontaneously without necessary of hardening the coacervate particles formed by using formalin or the like and hence the tendency of redispersing and aggregating of the coacervate particles is reduced, which increases further the stability of coacervates.

In the case of using polyvinyl alcohol, the polymer having a lower molecular weight is more profitable since the viscosity of the phthalic derivative thereof thus formed is not too high and also the use of incompletely saponificated polymer in which an acetyl group has been left, or theoretically speaking a copolymer of vinyl alcohol and vinyl acetate is more profitable in the point of solubility than the use of a completely saponified polymer.

Also, as mentioned above, the coacervation of this invention has a possibility of occuring in a wide range of pH different from the case of gelatin and gum arabic but the phthalic acid derivatives have different properties according to the raw materials for them. That is, the phthalic acid derivative of gelatin shows an acid property and tends to be precipitated by losing the water solubility of itself and further the phthalic acid monoester of polyvinyl alcohol is weak soluble in water at acid state and hence it is necessary, in this case, to conduct the coacervation in a neutral or weak alkaline state. On the other hand, because the phthalic acid ester of starch is difficult to be precipitated even at an acid state and has a good dispersibility, when the derivative is mixed with the cationic polymer rapidly without using a protective colloid, a good dispersion of the fine coacervates is easily obtained without forming the precipitates of large particles. While, since the phthalic acid derivative of gelatin or polyvinyl alcohol tends to be rapidly aggregated when it is brought into contact with the cationic polymer, the formation of the stable coacervates are generally difficult without use of a protective colloid but stable and fine coacervates are formed when a nonionic water-soluble polymer is employed as the protective colloid. The latter method is also applied effectively to the case of using the phthalic acid derivative of starch. This is also quite profitable since it is necessary in this invention that the coacervate particles are dispersed in a colloid as a binder. Therefore, although it is of course necessary to select properly a binder to be used as the protective colloid according to the purpose, the stability of it is concerned with the polymers composing the coacervate particles, the coacervate particles formed by utilizing the phthalic acid derivative of polyvinyl alcohol are gener ally more stable in polyvinyl alcohol than in gelatin, and such a combination shall be considered in this invention.

In addition, for utilizing practically the coacervate particles, they are mixed with a suitable amounts of a binder and a hardening agent and the mixture is applied to a support to provide a dye'transfer layer or in the case of using them in a silver dye bleaching method or in a filter layer, a suitable acid dye is added to them, the mixture is added, with or without washing by water, to a photographic emulsion, and the mixture is applied as a photographic emulsion layer. In any cases, the anionic dye molecule diffusible in an aqueous medium comes into contact with the nitrogen-containing polymer molecule at the surface of the coacervate particles, where other complex is formed and deposited thereon and hence becomes undiffusible, whereby the dye is fastly fixed thereto.

Thus, the mordant in this invention is composed of the coacervate particles and hence the dyes are dyed in particles but because the coacervate particles are dispersed finely and uniformly in a grain size ofO. 1-10 microns, the color tone and the resolving power thereof are almost same as those of the case where dyes are, on an average, dyed in a molecular state. Further, since in such case the dye itself forms a micelle to prevent the dye from being aggregated, the color tone is profitably constant from the high-dense portion to the low dense portion. Moreover, by the process of this invention, it is possible to disperse the nitrogen-containing cationic polymer having bad miscibility with a binder resin completely as fine particles and mix the polymer uniformly in the binder, the selection of mordant becomes quite freely, which makes the industrial merit of this invention larger.

In particular, in case of conducting a silver dye bleaching method, many of nitrogen-containing cationic compounds are difficult to be handled since they frequently tend to form fogs, impede the color sensitization, and sometimes act desensitizingly although some of them adsorb readily on silver halide grains and show a sensitizing property. But, according to the present invention, the mordant is separated from the surface of the photosensitive silver halide grains as well as the acid dye is also separated from the surface of the silver halide grains. Therefore, the occurrences of the hindrance of desensitization and fogs are further reduced and hence the selectivity of the mordant and the acid dye are further widened.

Moreover, it gives the following remarkable merits when the invention is applied to a transfer layer in a dye-transfer system that the mordant be dispersed in a binder as the form of separated particles. That is, in the case where the diffusible dye present or formed in a matrix or a light-sensitive emulsion layer transfers by diffusion into a binder layer of a transfer layer formed on the surface of a support, the surface of the binder layer having been contacted with the surface of the matrix or the light-sensitive emulsion layer at transferring, the dye diffuses into the inside of the layer by the aid of the density gradient but when the mordant is uniformly dispersed in the binder layer, the dye transfers quickly at the beginning owing to the strong adsorptive property but the diffusion speed of the dye in the inside of the layer is on the contrary reduced. On the other hand, in the case of this invention, the dye tends to diffuse in the transfer layer through the binder layer (e.g., gelatin or polyvinyl alcohol layer) present amongs the coacervate particles, said binder layer having a weak adsorptive property to the dye, without passing through the coacervate particles having a strong adsorptive property to the dye and hence the dye diffuses deeply in the transfer layer, where the dye is fixed to the surface of the coacervate particle or the mordant in the inside of the transfer layer, that is, the transfer speed is faster. Furthermore, the tendency of the dye once fixed on the coacervate particles diffusing into the adjacent layer over the intermediate binder layer among the coacervate particles becomes very low and hence the diffusion of the dye to the direction along the surface of the transfer layer is extremely reduced (reduced to the order of the distance between the particles). Therefore, in spite of the presence of the coacervate particles, a very sharp color print having less fogs and excellent resolving power is obtained.

In the case of conducting coloring of photographic layers such as photosensitive emulsion layers, a filter layer, and an antihalation layer of a light-sensitive element for silver dye bleaching method by utilizing the present invention, the coacervate-type mordant may be incorporated in a binder separately from the dye but after preliminary dyeing the coacervate particles with the dye in the dispersion state, the particles may be introduced in a photographic layer. The latter system is particularly profitable for the coloring of a sensitive photographic emulsion layer or an adjacent photographic layer in the points that the coacervate dispersion thus dyed are readily purified by water washing, dialysis, or other manner and also harmful impurities or foreign matters in the dye are readily removed.

As shown in the examples of this invention, when the coacervate particles are formed using gelatin as the protective colloid, the dispersion is coagulated by cooling, cut into needles or cubes, and then washed with water or the dispersion is precipitated in fine particles by adding aqueous magnesium sulfate solution and then after placing them in a net bag, they are washed with water. When polyvinyl alcohol is used as the protective colloid, the dispersion is placed in a cellophane bag and then washed with warm water by dialysis.

The invention will then be explained more practically by the following examples although the invention shall not be limited to them.

EXAMPLE 1 In 60 ml of water were dissolved 3 g of commercially available gelatin modified by phthalic acid (specific gelatin No. 2567 sold by LINER Co. of the U. K., which is believed to be one prepared by substituting 98 percent of the e-amino group in the gelatin molecule with phthalic acid) and 4 g of photographic gelatin and then the pH of the solution was adjusted to 6.0. To the solution was added a solution of 1.5 g of a benzylchloride salt of polymethacrylic acid dimethylamino-ethanol ester (Compound V shown above) as fine streams followed by stirring, whereby coacervates having a grain size of less than 1 micron were formed to provide a stable suspension. To the suspension was added 6 ml of 10 percent formaldehyde solution and the mixture was stirred for one hour while maintaining at the same temperature. The mixture was cooled slightly and then applied to a baryta-coated paper at about 34C in about g/m and dried to provide a transfer paper showing an excellent resolving power when used for imbibition printing. Also, instead of applying directly to a barytacoated paper, the transfer layer containing the coacervate particles was applied as a neutralizing layer to an under coat formed by dissolving in water a mixture of a copolymer of vinyl methyl ether and maleic anhydride (PVA/MA, GANTREZ AN" sold by GAF Co. of the U.S.A.) and gelatin and applying the solution to a paper in a dry amount of 10 g/m to provide a transfer paper suitable for preparing color print by a dye developer transfer system similar to Polacolor" system and also suitable for a color printing system in which a diffusible dye is treated by color development and then the dye is transferred to a transfer paper by an imbibition printing system as disclosed in British Pat. Nos. 840,731 and 904,364. In the system, the alkaline component in the developer diffused in the transfer paper from a light-sensitive element during transfer processing was neutralized by the neutralizing layer and hence the formation of yellow stains in the transfer layer with the passage of time was prevented without applying water washing. (Of course, water washing might be applied without accompanied with the lost of the dye by diffusion and ooze of dye image but the employment of water washing was undesirable in the point of printing speed.)

EXAMPLE 2 A solution of 3-4 g (the amount had to be controlled since it varied according to the purity and color tone of the commercially available dye) of a decoloring acid azo dye suitable for a silver dye bleaching method (Chicago Blue 68 (CI. 24410) was preferable as blue dye, Diamine Rose (CI. 15080) was suitable as magenta dye, and Brilliant Yellow (CI. 24890) was suitable as yellow dye) in 150 ml of water was added to 100 ml of the coacervate dispersion prepared by the same way as in Example 1 and after stirring the mixture for 30 minutes at 50C, the mixture was set by cooling and washed with water at -l5C, whereby soluble impurities in the dye were washed away and quite pure and photographically harmless gelatin coloring agent in which the dye had completely dyes to the coacervate particles containing the mordant of this invention was obtained.

The above-mentioned amount of the coacervatecontaining gelatinous dispersion prepared above was a such amount as suitable for preparing a multiple layer type color photographic light-sensitive element to be processed in a silver dye bleaching method by adding to 600 g of a silver halide emulsion prepared from mainly about 40 g of gelatin and g of silver nitrate but the amount may be varied.

EXAMPLE 3 In a three-necked flask equipped with a silica tube, 100 g of polyvinyl alcohol having a polymerization degree of about 500 (Kurare Poval No. 105, trade name, made by Kurare Co.) was dispersed in 1 liter of glacial acetic acid and then after adding 250 g of phthalic anhydride, 100 g of maleic anhydride, and 75 g of anhydrous sodium acetate to the dispersion, the system was reacted for 10 hours at 95C with stirring. The reaction product was poured in 8 liters of acetone to form precipitates, which were recovered by filtration, washed with acetone, and dried to provide 450 g of a pure white powder. It was difficult to determine accurately the esterification degree but it was assumed that the product contained about 50 percent by weight of the phthalic acid monoester and about 10 percent by weight of the maleic acid monoester.

Because the power thus obtained was not dissolved in water at an acid state but could be dissolved in water when the acid water was neutralized with an alkali, 5 g of the powder was dissolved in 100 ml of weak alkaline water and after adjusting the pH of the solution to 6.5, the solution was mixed with 100 ml of a 5 percent solution of polyvinyl alcohol having a polymerization degree of 1,000 and a saponification degree of 95 percent followed by stirring vigorously at 50C. When 100 ml of 5 percent aqueous solution of poly-2- vinylpyridine having the formula (I) mentioned above acidified by acetic acid to 3.0 was poured in the mixture at room temperature, coacervates of 2-3 microns in diameter were formed immediately. The system was then heated to 50C for 10 hours to proceed the cross linkage by the maleic acid residual group, whereby the coacervate particles were sufficiently hardened. The coacervate particles thus obtained were hard to be set different from the case of using gelatin but because molds were less formed and the coacervate particles were not decomposed, the product was profitable for preservation.

Just before coating, 2 ml of 10 percent formalin and 1 ml of triethanolamine were added to 100 ml of the dispersion prepared above and then the mixture was applied to a baryta-coated paper having an under coat formed by coating the paper with 2 percent aqueous solution of boric acid and dried to provide a transfer paper quite suitable for imbibition printing.

EXAMPLE 4 A phthalic acid monoester of starch prepared by reacting for one hour 50 g of a commercially available soluble starch and 68 g of phthalic anhydride in 200 ml of formamide using 37.5 g of anhydrous sodium acetate as the catalyst at temperatures of lower than 60C was added to 1.2 liters of acetone to form precipitates, which were recovered and washed with methanol and then acetone to provide about 87 g of a white powder of the product of which about percent of the carboxyl group had been converted into the sodium salt. The substitution percentage of the product was 35 percent (the product contained, on an average, 1.05 phthalic acid residual groups per one glycose unit. The product (5 g) was dissolved in 150 ml of water together with 5 g of gelatin and after adjusting the pH of the solution to 6.5, the solution was heated to 50C.

Apart from this, an aqueous solution of amino.guanidized dialdehyde starch was prepared. In this case, since a commercially available amino.guanidized dialdehyde starch had a low amino.guanidization (about 5 percent), the material was prepared by dispersing of a commercially available dialdehyde starch (SUMASTAR-ISO having an oxidation degree of about 50 percent, made by Miles Co.) in 300 ml of water, adding a solution of 45 g of aminoguanidine hydrochloride in 450 ml of water to the dispersion at a pH of 2, and reacting them for 20 hours at room temperature in accordance with the method stated in Example 2 of Japanese Pat. application No. 7754/68 filed by the same inventors. ln the product, about a half of the whole aldehyde groups had been amino guanidized and the product was a mordant having excellent adsorptive property to dyes. in 50 ml of water was dissolved 2.5 g of the product by heating and after adjusting the pH of the solution to 6.5, the solution was cooled to room temperature.

While vigorously stirring the mixed solution of gelatin and the phthalic acid-modified starch prepared before, the solution of the amino guanidized dialdehyde starch was poured in the mixed solution to make the whole volume to 200 ml, whereby coacervates were formed. The formation of the coacervates was confirmed by a microscopic examination. In the product was further dissolved 5 g of gelatin and the system was further heated to 50C for 2 hours. The coacervate dispersion thus finished was gelatinized by cooling and then preserved.

A transfer sheet for imbibition printing was prepared by adding 2 ml of 10 percent formaldehyde solution to 100 ml of the solution prepared above and applying the solution to a baryta-coated paper or a triacetate base with or without the formation on the sheet or the base a neutralizing layer composed of gelatin and a copolymer of vinyl methyl ester and maleic anhydride as shown in Example 1.

In this case, because about a half of the aldehyde groups of the raw material remained as it was in the amino guanidized dialdehyde starch, a cross linking reaction occurred in the coacervate particles to harden the particles as well as to cause cross linking reaction with the gelatin molecules surrounding the particles without adding particularly a hardening agent and hence the transfer layer thus obtained was sufficiently hardened with a small amount of formalin and showed a proper degree of swelling.

EXAMPLE 5 The coacervate dispersion (200 ml) prepared by the same manner as Example 4 was coagurated by cooling. The coagurated dispersion was finely cut into needles as photographic emulsion, placed in a net bag of nylon having such coarse mesh as gauze, and then the bag was immersed for l hour at 20C in a solution of 0.75 g of the decoloring yellow acid dye having the following formula,

The gel was then washed with running water for 1 hour at C and dissolved. The solution was coated as an intermediate layer of about 90 g/m between the uppermost yellow layer and a magenta color forming layer or a cyan color forming layer on a multiple layertype color photographic light-sensitive element. The intermediate layer acts as a yellow filter layer for removing the specific sensitivities of the light-sensitive emulsion layers disposed under the intermediate layer at exposure and is decolored during the development and fixing processings. Therefore, the yellow layer is useful as a filter layer giving no bad influences on the final dye images. The layer is also useful for color photographic light-sensitive elements for color developing system, silver dye bleaching system and ones having multiple layers of dye-sensitized silver halide emulsion layers.

The important merits of this invention are that the dye is fixed stably and fast to the intermediate filter layer during the drying of the multiple layer type color photographic light-sensitive element as well as the preservation of the non-exposed light-sensitive element without diffusing into adjacent layers and also the coloring of the photographic layer by such a kind of dye which is comparatively unstable is practiced easily and very uniform dyeing having no unevenness becomes possible.

What is claimed is:

l. A mordanting process for color printing materials which comprises using a dispersion of fine coacervate particles suitable for fixing anionic coloring matter onto a surface, said particles having been prepared in the form of a complex by reacting a protective colloid, a monoester of phthalic acid or phthalic anhydride and a water soluble polymer selected from the group consisting of starch and polyvinyl alcohol or a monoamide of phthalic acid or phthalic anhydride and gelatin and complexing the free acid group of said monoester or monoamide with a high molecular weight cationic nitrogen-containing basic vinyl polymer to form a coacervate mordant, said coacervate mordant having particle sizes of from 0.1 to 10 microns.

2. The process of claim 1 wherein part of the phthalic acid or phthalic anhydride used to form the monoamide is replaced with maleic acid or acetic acid, the protective colloid is a water-soluble polymer and the surface is a photographic layer.

3. A mordanting process for fixing acid dyes onto a photographic emulsion layer which comprises using the product prepared by complexing in an aqueous medium containing a protective colloid a reaction product obtained by monoamidifying gelatin with phthalic acid and comprising the free acid group with benzyl chloride salt of polymethacrylic acid dimethylaminoethanol ester to form a coacervate polymeric mordant, said coacervate mordant having particle size of from 0.1 to 10 microns.

4. A mordanting process for fixing acid dyes onto a photographic emulsion layer which comprises using the product prepared by complexing in an aqueous medium containing a protective colloid, a reaction product obtained by monoesterifying polyvinyl alcohol with a mixture of phthalic anhydride and maleic anhydride, said complexing monoester modified polyvinyl alcohol with poly-2-vinyl pyridine, said complex having particle sizes of 2-3 microns.

5. A mordanting process for fixing acid dyes onto a photographic emulsion layer which comprises using the coacervate mordant prepared by complexing in an aqueous medium containing a protective colloid, a reaction product obtaining by monoesterifying a soluble starch with phthalic anhydride and complexing the carboxyl groups with aminoguanidized dialdehyde starch, said complex having particle size of from 0.1 to 10 microns.

6. The process of claim 1 wherein said polymer having the nitrogen-containing group is selected from the group consisting of poly-2-vinyl pyridine, methyl p-toluenesulfonate of poly-4-vinyl pyridine, poly-4-vinylbenzyl-trimethyl ammonium chloride, poly-4-vinylbenzyl-triethanol ammonium chloride, benzyl chloride of polymethacrylic acid dimethylamino ethanol ester or, acetate of partially amino guanidized polyvinyl methyl ketone.

7. A mordanting process for fixing acid dyes onto a photographic emulsion layer which comprises using the product prepared by complexing in an aqueous medium containing a protective colloid, a reaction product obtained by monoesterifying polyvinyl alcohol with phthalic anhydride and complexing said monoester modified polyvinyl alcohol with poly-2-vinyl pyridine, said complex having particle sizes of 2-3 microns. 

2. The process of claim 1 wherein part of the phthalic acid or phthalic anhydride used to form the monoamide is replaced with maleic acid or acetic acid, the protective colloid is a water-soluble polymer and the surface is a photographic layer.
 3. A mordanting process for fixing acid dyes onto a photographic emulsion layer which comprises using the product prepared by complexing in an aqueous medium containing a protective colloid a reaction product obtained by monoamidifying gelatin with phthalic acid and comprising the free acid group with benzyl chloride salt of polymethacrylic acid dimethylaminoethanol ester to form a coacervate polymeric mordant, said coacervate mordant having particle size of from 0.1 to 10 microns.
 4. A mordanting process for fixing acid dyes onto a photographic emulsion layer which comprises using the product prepared by complexing in an aqueous medium containing a protective colloid, a reaction product obtained by monoesterifying polyvinyl alcohol with a mixture of phthalic anhydride and maleic anhydride, said complexing monoester modified polyvinyl alcohol with poly-2-vinyl pyridine, said complex having particle sizes of 2-3 microns.
 5. A mordanting process for fixing acid dyes onto a photographic emulsion layer which comprises using the coacervate mordant prepared by complexing in an aqueous medium containing a protective colloid, a reaction product obtaining by monoesterifying a soluble starch with phthalic anhydride and complexing the carboxyl groups with aminoguanidized dialdehyde starch, said complex having particle size of from 0.1 to 10 microns.
 6. The process of claim 1 wherein said polymer having the nitrogen-containing group is selected from the group consisting of poly-2-vinyl pyridine, methyl p-toluenesulfonate of poly-4-vinyl pyridine, poly-4-vinylbenzyl-trimethyl ammonium chloride, poly-4-vinylbenzyl-triethanol ammonium chloride, benzyl chloride of polymethacrylic acid dimethylamino ethanol ester or, acetate of partially amino guanidized polyvinyl methyl ketone.
 7. A mordanting process for fixing acid dyes onto a photographic emulsion layer which comprises using the product prepared by complexing in an aqueous medium containing a protective colloid, a reaction product obtained by monoesterifying polyvinyl alcohol with phthalic anhydride and complexing said monoester modified polyvinyl alcohol with poly-2-vinyl pyridine, said complex having particle sizes of 2-3 microns. 